High speed automatic lathe

ABSTRACT

A high speed automatic lathe having a chuck which can rotate at high speeds without vibration such as would cause damage to the quality of work turned out thereby. The chuck is of the collet type and is circumferentially symmetrical so that possible causes of vibration are absent.

Umtefl States Patent 1191 1111 3,752,619 Kameko Aug. 14, 1973 1 HIGHSPEED AUTOMATIC LATHE FOREIGN PATENTS OR APPLICATIONS [75] Inventor;Yoshizada K n 'k Ok yjpan 842,147 6/1952 Germany 82/28 73 A s' nee:Kabushiki Kaiska Suw Se 21 11 l 5 lg Tokyo Japan a s PrimaryExaminer-Leonidas Vlachos Attorney-Alex Friedman, Harold 1. Kaplan eta1. [22] Filed: July-27, 1971 21 Appl. No.2 166,357 V 57 ABSTRACT [52]US, Cl......' ..82/281R, 279/4 [51] Int. Cl. B231) 19/00 A high speedautomatic lathe having a chuck which can [58] Field of Search 82/28, 30;279/4, rotate at high speeds without vibration such as would 279/43, 50,57 cause damage to the quality of work turned out [56] References Citedthereby. The chuck is of the collet type and is circumferentiallysymmetrical so that possible causes of vibra- UNITED STATES PATENTS Vtion are absent 1,185,681 6/1916 Kienzle 82/28 3,168,322 2/1965 Dziedzic3,643,969 2/1972 Finley 279 4 2 Claims 2 Drawmgmgum 1 4 Q 6 Z 3 l i 2 U& F '32 2 1 25 27 men SPEED AUTOMATIC LATHE BACKGROUND OF THE INVENTIONWith the objective of increasing the output of automatic lathes it isdesirable to increase the rotation speed at which they operate andthereby the cutting speed. Up to the present time rotation speed formost automatic lathes has been limited to 7,000 to 8,000 rpm. Attemptsto raise the speed of rotation has resulted in vibration of the spindleand decrease in tool life, processing precision, and machine life.

Chucking devices used up to now for high-speed lathes have been a toggletype and a fluid-operated type using air pressure or oil pressure. Inthe toggle type, vibration is generated by the presence of theunbalanced toggle which causes pressure againstbearings and in 1consequence, shortens life. The fluid-operated type, while introducingno problem of unbalance, has introduced a sealing problem. In theconstructions used to date, leakage has almost invariably beenencountered. Th difficulty arises from the need to effect a satisfactoryseal between a fixed portion and a rotating portion of the pressuredevice. Moreover, for high speed rotation, the life of the sealing meanshas been unsatisfactorily short.

SUMMARY OF THE INVENTION A chuck which can be rotated at high speedwithout vibration and without leakage of fluid includes a collet, achuck sleeve and a spindle where the spindle is coaxial with and fixedto a rotor and the rotor is surrounded by a stator. The stator is fixedin a headstock frame so that the motor is, in effect, integral with theheadstock. As a result, the motor, the spindle, the chuck sleeve and thecollet can rotate at high speed without vibration. A biasing meansplaced between the chuck sleeve and the spindles displaces the chucksleeve in a direction such that it grips the collet and closes it upon aworkpiece. To remove a workpiece from the collet or to move a workpieceaxially through the collet, the chuck sleeve is moved against the urgingof the biasing means so as to permit the collet to open and release theworkpiece Movement of the chuck sleeve in this direction relative to thespindle is effected by-a displacing means such as a piston in a cylinderor by a solenoid and armature. The displacing means rotateswith thespindle and chuck sleeve.'

Accordingly, anobject of the present invention is to provide a chuckrotatable at higher speeds than has hitherto been possible.

Another object of the invention is to provide a chuck rotatable at highspeeds while free of vibration which would shorten tool life anddecrease the precision of workmanship.

A further object of the invention is to provide an automatic lathe 'witha chuck rotatable at higher speeds than hitherto has been possible,thereby increasing cutting speed and production.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts which will beexemplified in the construction hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of theinvention, reference is had to the following description taken inconnection with the accompanying drawing, in which:

FIG. ll shows in longitudinal section an automatic lathe chuck inaccordance with the present invention; and

FIG. 2 shows an end view of the same chuck.

DESCRIPTION OF THE PREFERRED EMBODIMENT In a high speed automatic lathechuck in accordance with the present invention to hollow spindle 6 haswithin it a chuck sleeve 2. The chuck sleeve 2 grasps a collet chuck 3in closed position, that is to say, when holding a workpiece (notshown). The collet chuck 3 is held to the spindle 6 by means of aspindle cap 4. The chuck sleeve 2 is urged to the left by biasing means1, in this case a spring. As a result of the flexibility of the spring1, the chuck sleeve 2 can be displaced axially to the right.

The spindle 6 is mounted rotatably on a headstock frame 8 by bearings 9and 13. A rotor 12b keyed by key 11 to spindle 6 cooperates with astator 12a fixed to headstock frame 8. The bearing 9 is fixed toheadstock frame 8 by bearing fixing plate 7 and screw 10. Bearing 13 isfixed to the headstock frame 8 by bearing support 23. The combination ofstator 112a fixed to the headstock 8 and rotor 12b fixed to the spindle6 which is supported by the bearings Q and 13 results in a motor drivecombination which is free of vibration at extremely high speeds.Variation in rotation speed is provided by a frequency changer (notshown).

Pipe 15 supplies pressurized fluid, preferably compressed air, throughbearing support 23 and bearing side connector 32 to passages 25traversing cylinder wall 20. Cylinder 20 is fixed to spindle 6 by key 14and is held in position by nut 22. Pressurized fluid enters space 29formed between piston 19 and cylinder 20. Piston 19 is fixed to chucksleeve 2 by key 17 and is held in position by nut 18. Introduction offluid into space 29 at sufficiently high pressure moves the chuck sleeve2 against the pressure exerted by spring 1 and opens collet 3 fordisplacement of work insertedthrough hollow 23 in chuck sleeve 2.

Seal between piston 19 and cylinder 20 is effected by O-ring 16. Sealbetween bearing side connector 32 and cylinder 20 is effected by packing24 having a labyrinthine shape. 1

Pipe 15 may be supplied with air from pipe A through valve 26. When thevalve 26 is open air from pipe A travels through pipe C toward pipe 15.Pipe B serves for venting of air. Valve 26 is controlled by cam 27through switch 31. I

To operate the chuck, headstock 8 is moved into proper position on bed21 by means which are not shown. Cam 27 is rotated to close switch 31opening valve 26 so that air is introduced into the cylinder and thechuck is thereby opened. A workpiece in the form of a bar is insertedthrough passage 23 into collet 3. Cam 27 rotates further opening switch31 and venting air from the cylinder out through outlet B.'The chuck,closes, the workpiece is machined and cut off, cam 27 re-opens valve 31,the cylinder is pressurized, the work piece is moved forward by-apredetermined amount,

pressure is vented from the cylinder and theprocess continues, thespindle with the chuck sleeve and collet rotating throughout.

Since the motor is fixed inside the headstock frame, loading on thebearings is small and the rotation of the spindle is uniform resultingin increased precision of machining and increased length of life for themachine. Moreover, since the spindle is coaxial with the motor there isno noise of driving gears, or belt drive.

In contrast with the toggle type chuck, the chuck sleeve is operatedonly whenthe chuck is being opened, since the spring takes care ofclosing the collet. Also the centrifugal force which causes the toggletype chuck to vibrate is completely absent since the system isdynamically symmetrical. The fact that the chuck sleeve moves onlyaxially during operation of the collet means that loading of thebearings during opening and closing of the collet is absent.

The movement of the chuck sleeve relative to the spindle and the colletcould also be effected electrically. Thus, an electromagnetic coil couldbe mounted on the end of the spindle and an armature coaxial with thecoil could be mounted on the chuck sleeve. Sliding contacts would, ofcourse, be necessary.

In the absence of a toggle and the cam and lever necessary to operatesuch a device, remote control becomes possible, as is indicated in FIG.1.

In a high speed chuck of the present invention, a sealing member such asthe conventional connector for fluid is not used. Also, a gap 33 isprovided so that rotating cylinder and stationary bearing side connector32 do not touch each other; consequently, it is unnecessary to supplyoil to parts rotating at tens of thousands of rpm so that there is nowear from this factor. Consequently, maintenance is simply and easy andreliability is high. In accordance with the present invention, if abearing side connector is in a body with a bearing holder or isconstructed separately, the same effect is obtained.

The chuck of the present invention is not restricted to high speedautomatic lathes, but is also suitable for use in lathes operating atmore conventional speeds.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in the above construction withoutdeparting from the spirit and scope of the invention, it is intendedthat all matter contained in the above description or shown in theaccompanying drawing shall be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:

1. A chuck for high speed automatic lathe comprising a headstock frame,'a spindle rotably mounted in said frame, a chuck sleeve slidablymounted in said spindle, a collet within said chuck sleeve for holding aworkpiece, said collet being fixed to said spindle proximate one endthereof, biasing means urging said chuck sleeve in one axial direction,the direction being such as to cause said collet to close and remain inclosed position, a motor rotor fixed to said spindle, a motor statorfixed to said frame bearings in said frame exterior to said motor andholding said spindle for rotation therein; a cylinder member having ahead at one end thereof, a skirt fixed to said head end and attached tosaid spindle for rotation therewith, said skirt having an annular groovearound the outer periphery thereof and having a conduit thereinconnecting said groove with the interior of said cylinder member, apiston member in said cylinder, said piston member being attached tosaid chuck sleeve for rotation therewith and fitting sealingly andslidably in an axial direction within said cylinder member, a source ofpressurized fluid attached to said frame, and gasket means within saidframe disposed proximate to said skirt on both sides of said groove forminimizing leakage of presurized fluid between said gasket and saidskirt, said gasket being apertured and said source of pressurized fluidbeing so located in said frame that fluid can pass in either directionbetween said source and the interior of said cylinder member throughsaid gasket aperture, said skirt groove and said skirt conduit.

2. The clutch as defined in claim 1 further comprising vent means forventing pressurized fluid from said cylinder member, and switching meansfor selectively pressurizing said cylinder means to open said chuckcleeve, and venting said cylinder member thereby permitting said pistonmeans to move toward said head end of said cylinder means under theurging of said biasing means for closing said chuck sleeve.

1. A chuck for high speed automatic lathe comprising a headstock frame,a spindle rotably mounted in said frame, a chuck sleeve slidably mountedin said spindle, a collet within said chuck sleeve for holding awork-piece, said collet being fixed to said spindle proximate one endthereof, biasing means urging said chuck sleeve in one axial direction,the direction being such as to cause said collet to close and remain inclosed position, a motor rotor fixed to said spindle, a motor statorfixed to said frame bearings in said frame exterior to said motor andholding said spindle for rotation therein; a cylinder member having ahead at one end thereof, a skirt fixed to said head end and attached tosaid spindle for rotation therewith, said skirt having an annular groovearound the outer periphery thereof and having a conduit thereinconnecting said groove with the interior of said cylinder member, apiston member in said cylinder, said piston member being attached tosaid chuck sleeve for rotation therewith and fitting sealingly andslidably in an axial direction within said cylinder member, a source ofpressurized fluid attached to said frame, and gasket means within saidframe disposed proximate to said skirt on both sides of said groove forminimizing leakage of presurized fluid between said gasket and saidskirt, said gasket being apertured and said source of pressurized fluidbeing so located in said frame that fluid can pass in either directionbetween said source and the interior of said cylinder member throughsaid gasket aperture, said skirt groove and said skirt conduit.
 2. Theclutch as defined in claim 1 further comprising vent means for ventingpressurized fluid from said cylinder member, and switching means forselectively pressurizing said cylinder means to open said chuck cleeve,and venting said cylinder member thereby permitting said piston means tomove toward said head end of said cylinder means under the urging ofsaid biasiNg means for closing said chuck sleeve.